Re: locking diffs? was: Boating with an S4

[ti@amb.org (Ti Kan)]

Damon Cassell writes:
> you mention that it's all wheel drive, all of the time.  so, this is unlike
> the AWD systems on a Honda CRV or a subaru, right?  i believe those systems
> are primarily FWD but direct a certain percentage of power to the rear
> wheels when necessary.  all four audi wheels are powered simultaneously even
> on a flat, dry surface?

Yes, all Audi quattros have four driven wheels, each getting 25% of the
torque on flat dry surfaces.  The exception to this are the new TT quattro
(and the Euro A3 quattro and and S3), which have a Haldex system that
is FWD until it senses a slip and transmit torque backwards.  Also, the
new bi-turbo S4 has the 4th-gen quattro but the standard torque split
is slightly rearward, something like 45%/55% (I forgot the exact numbers).

Here is a summary of Audis quattro system history (with a US model slant).
Generation 1-4 are all full-time all wheel drive.

1st generation (circa 1982-1987):
Open differential in front, manually lockable differentials in
center and rear.
Quattro turbo coupe (urQ), 4000S/CS quattro, 5000CS quattro.

2nd generation (circa 1988-1995):
Open differential in front, Torsen center differential, manually
lockable rear differential.
88-92 80/90 quattro, 90-91 Coupe quattro, 89-91 100/200 quattro,
92-94 100 quattro, 92-94 S4, 95 A6 quattro, 95 S6.

A variation of the 2nd generation (1993):
Same as 2nd-gen except the rear differential is a Torsen too.
93 V8 manual

3rd generation (circa 1990-93):
Open differential in front, electronically controlled multi-plate clutch
center differential, Torsen rear differential.
90-93 V8 automatic

4th generation (circa 1996-now):
Open differentials front and rear, Torsen center differential.
Electronic differential lock (EDL).
95.5 S6, 96-00 A4 quattro, 96-00 A6 quattro, 97-00 A8 quattro,

Again, this is with a US model slant.  The Euro urQ got the
2nd-gen system in 90(?) but the urQ was only imported to the US
up to 85.

-Ti
96 A4 2.8 quattro
84 5000S 2.1 turbo
80 4000 2.0
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti@amb.org
 //////  http://metalab.unc.edu/tkan/
///